Vacuum circuit interrupter with a plurality of interrupting units

ABSTRACT

In a vacuum circuit interrupter of the type having two or more identical interrupting units mounted within an evacuated housing, a plasma screen is formed for the arc created by interruption of the current between a stationary and a movable contact for each of the interrupting units by a helicoidal winding of conductive material electrically connected with the electric current circuit of the associated interrupting unit for the generation of a magnetic field which encloses the plasma generated therein.

[ Mar. 11, 1975 United States Patent [1 1 Clason 11/1972 Schonhuber.................... ZOO/144 B VACUUM CIRCUIT INTERRUPTER WITH A PLURALITY OF INTERRUPTING UNITS b e \g n e H n 0 S a I C n as old mn rm m m 6 MN n O t n e v n l l 5 7 l Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-Watson, Cole, Grindle & Watson Hengelo,

[73] Assignee: Hazemeijer B.V

Netherlands ABSTRACT [22] Filed: Oct. 25, 1973 In a vacuum circuit interrupter of the arc created by interruption of the current between 21 Oct. 27, tationary and a movable ontact for each of the inte u rupting units by a helicoidal winding of conductive U-S- C l-...........-.............. B, R material electrically connected the el tri r [51] Int. Cl. H01h 33/66 rent circuit of the associated interrupting unit for the generation 0 [58] Field of Search 200/144 B, 147 R f a magnetic fi ld which encloses the plasma generated therein. [56] References Cited UNITED STATES PATENTS 3 Claims, 2 Drawing Figures 2,906,841 9/1959 Jennings.......................... 200/144 B PATENTED HARI 1 I975 iiiii VACUUM CIRCUIT INTERRUPTER WITH A PLURALITY OF INTERRUPTING UNITS The invention relates to a vacuum circuit interrupter having two or more identical interrupting units arranged in one evacuated housing, each interrupting unit comprising a stationary contact and a movable contact, and each being provided with a plasma screen, which blocks the access to the other interrupting units of the plasma generated at the interrupting process of a particular interrupting unit. Such apparatus is disclosed in the leaflet of.loslin D. B. 751-201, August 1971.

The known circuit interrupter comprises three evacuated spaces, each of which including three one phase interrupters. The corresponding interrupters in the three evacuated spaces are mechanically coupled and constitute a three phase interrupter, the three contacts of which being arranged respectively in different vacuum spaces. Hence each vacuum space includes three interrupting units, which can be operated independently one from another. Each interrupting unit is provided with a plasma screen of ceramic material, acting to separate the plasmas of the various interrupting units. For if two interrupting units are opened and the third one is closed, and if the'third interrupting unit would be opened in absence of the plasma screens, the plasma of thethird unit would enter between the opened contacts of the two remaining interrupting units, whereby the latter'might break through. It is this phenomenon which is prevented with the ceramic plasma screens.

According to present invention it has been found that the ceramic plasma screens can be omitted, if the three one phase interrupting units are provided with three respective axial magnetic fields, which are generated by the electric currents, flowing through the interrupting units. I

The invention provides an apparatus of the type defined above, which is characterized in that each plasma screen is constituted as a helicoidal winding of conductive material, which is electrically inserted into the electric current circuit of the associated interrupting unit, said helicoidal winding generating a magnetic field, which encloses the plasma of the associated interrupting unit.

According to a preferred embodiment the apparatus according to the invention is so arranged, that the helicoidal winding of each interrupting unit carries a contact at one end and is provided with a connecting rod at the other end, said connecting rod being brought out of the housing vacuum tight, while the other contact is arranged on a contact rod, which at least over a part of its length is coaxially arranged in the helicoidal winding.

A further important advantage of said arrangement is that the disturbing influence on the electric interrupting arc of the electromagnetic field which is generated by the current conductors connected to the contacts, whichinevitably have an'unfavourable form in known structures, is eliminated to a large extent.

It is known that an interrupting arc is quenched more easily if it can be restricted to the spacing between the contacts.

With the circuit interruptor according to present invention this is achieved by amplification of the electromagnetic field in the spacing between the contacts and a mitigation of the unfavourable influence on the field of the current conductors connected to the contacts by a coaxial arrangement of theconductorsf It is possible to mechanically couple the interrupting units with one another and to operate them together, so that the vacuum circuit interruptor is a plural phase interrupter.

It is observed that providing axial magnetic fields with one phase vacuum circuit interrupters, with which accordingly in one vacuum space one set of contacts is arranged, is described in the German Auslegeschrift" 1.273.66l. In that apparatus, however, the axial fields are only applied to improve the interrupting characteristic of the circuit interrupter. In the aforesaid German Auslegeschrift it has not been disclosed that axial magnetic fields are also useful for enclosing the plasma.

Finally it is observed that the Dutch patent specification 60.004 also discloses a three phase interrupter in vacuum. However, such a known circuit interrupter is an isolator, which as is known cannot interrupt electric currents of some importance, so that the problem of the plasma transfer from one interrupting unit to another does not occur in such an interrupter.

The invention will now further be explained in reference to the annexed drawing, in which;

FIG. 1 is a cross-section of a vacuum circuit interrupter having three interrupting units according to present invention along the line l] in FIG. 2, and

FIG. 2 is a cross-section alongthe line llll in HO. 1.

The vacuum circuit interrupter comprises a common evacuated housing 1, in which three interrupting units 2a, 2b and 20, respectively, are arranged. The three interrupting units 2a, 2b and 2c are in open communication with the interior of the common evacuated housing 1 through the helicoidal windings 11a, 11b and 11c. Each interrupting unit 2a, 2b and 20 comprises a movable contact member 3a, 3b and 30, respectively, which is arranged on a contact rod 4a, 4b and 40, respectively, which through a bellows 5a, 5b and 5c, respectively, is connected vacuum tight to an insulator 6a, 6b and 60, respectively, which in turn is coupled vacuum tight to the housing 1. The contact rod 4a, 4b and 4c can be moved up and down according to the arrows, and thereby the contact member 3a, 3b, 30 can be brought into engagement with or can be separated from the corresponding stationary contact member 7a, 7b, 70, which is in the form ofa projection or lump on the bottom of a pot 8a, 8b, 80, which is disposed upside down and is provided with the connecting rods 90, 9b, 90, which are brought out of the housing 1 in a vacuum tight fashion by means of the insulators 10a, 10b, 10c. Each pot 8a, 8b, 8c partially consists of a helicoidal winding 11a, 11b, which conducts the current flow in the associated interrupting unit, so that in each interrupting unit 2a, 2b, 2c an axial magnetic field is generated, which is oriented parallel to the axis of the contact rod 4a, 4b, 40.

It is found that with this vacuum circuit interrupter both one phase and three phase switching operations can be performed without the necessity of special ceramic screens around the three contact units.

In FIG. 2 additionally illustrated are the take-off contacts and 120, with which the current of the movable contact rod 4a, 40 is passed on to the stationary connecting rods 13a, 130. In FlG. 2 the parts 2b through 13b are not visible of course.

What we claim is:

1. In a vacuum circuit interrupter of the type' having two or more identical interrupting units arranged in one evacuated housing, each interrupting unit'having a stationary contact and a movable contact, and a plasma screen, which blocks access to the other interrupting units of the plasma generated by the interrupting pro-' cess of a particular interrupting unit, the improvement comprising: a helicoidal winding of conductive material electrically connected with the electric current circuit of the associated interrupting unit, said helicoidal winding generating a magnetic field for enclosing the plasma of the associated interrupting unit.

- ZQApparatus according to claim 1, wherein the helirod being at least over a part of its length coaxially arranged in said helicoidal winding.

3. Apparatus according to claim 1, wherein the interrupting units are mechanically coupled'and are-operated together whereby the vacuum circuit interrupter is a plural phase circuit interrupter. 

1. In a vacuum circuit interrupter of the type having two or more identical interrupting units arranged in one evacuated housing, each interrupting unit having a stationary contact and a movable contact, and a plasma screen, which blocks access to the other interrupting units of the plasma generated by the interrupting process of a particular interrupting unit, the improvement comprising: a helicoidal winding of conductive material electrically connected with the electric current circuit of the associated interrupting unit, said helicoidal winding generating a magnetic field for enclosing the plasma of the associated interrupting unit.
 1. In a vacuum circuit interrupter of the type having two or more identical interrupting units arranged in one evacuated housing, each interrupting unit having a stationary contact and a movable contact, and a plasma screen, which blocks access to the other interrupting units of the plasma generated by the interrupting process of a particular interrupting unit, the improvement comprising: a helicoidal winding of conductive material electrically connected with the electric current circuit of the associated interrupting unit, said helicoidal winding generating a magnetic field for enclosing the plasma of the associated interrupting unit.
 2. Apparatus according to claim 1, wherein the helicoidal winding of each interrupting unit carries said stationary contact at one end and further includes a contact rod supporting said movable contact at one end thereof adjacent said stationary contact, a connecting rod at the other end of said helicoidal winding being brought out of the housing vacuum tight, said contact rod being at least over a part of its length coaxially arranged in said helicoidal winding. 